单纯型卵巢无性细胞瘤的MRI诊断

MRI diagnosis of pure ovarian dysgerminoma

目的探讨单纯型卵巢无性细胞瘤的MRI表现。方法回顾性分析6例经手术病理证实的单纯型卵巢无性细胞瘤患者的临床、MRI及病理资料,总结其MRI表现。结果 6例肿块均位于单侧,肿块平均长径15 cm,呈类圆形、类椭圆形及哑铃状,包膜完整、边界清楚。4例为实性肿块伴坏死或囊变,2例为实性为主的囊实性肿块,实性部分T1WI呈等信号、T2WI呈稍高信号,坏死及囊性部分T1WI呈低信号、T2WI呈高信号;T2WI上见低信号纤维间隔将肿块分隔成多发小叶样改变。4例见流空血管影。DWI见实性部分呈高信号。增强扫描实性部分呈渐进性强化,动脉期呈轻度强化,静脉期呈中度强化,平衡期呈持续中度强化,纤维间隔及包膜呈渐进性明显强化。结论单纯型卵巢无性细胞瘤的MRI典型表现为低信号纤维间隔将肿块分隔成多发小叶样改变,结合患者年龄可作出诊断。

Objective To investigate the specific MRI manifestation of pure ovarian dysgerminoma.Methods The clinical, pathologic data and MRI findings in six patients with pure ovarian dysgerminoma confirmed by operation and pathologic examination were retrospectively analyzed.Results The masses of six patients were unilateral.The mean diameter was 15 cm.Six cases showed nearly-round, nearly-oval, or dumbbell in shape with intact capsule and clear boundary.Four masses mainly appeared as solid masses with necrosis and cystic lesions, two masses were cyst-solid mixed, but predominantly appeared as solid.The solid part of masses showed slightly isointensity on T1-weighted images, and slightly hyperintensity on T2-weighted images.The necrosis and cystic part showed hypointensity on T1-weighted images, and hyperintensity on T2-weighted images.Low signal fibrovascular septa in tumor was observed, and the tumor was divided into lobules by the fiber intervals.Many signal voids of vessel in tumors were observed in four cases.The solid part of masses showed slightly hyperintensity on DWI.The tumor was slightly enhanced in the arterial phase, moderately enhanced in the venous phase, and held moderately enhanced after the administration of Gd-DTPA.The fibrovascular septa and capsule were obviously enhanced.Conclusion The image feature of pure ovarian dysgerminoma is the hypointensity fibrovascular septa dividing the tumor into lobules, the qualitative diagnosis can be made combining with the age of patient.